Summary

Dystrophia myotonica is hereditary and causes systemic effects subsequent to myotonia and muscular atrophy. Pathohistological findings in the muscle fibre and the terminal plate are characteristic. Physiopathological theories are numerous and are related to metabolic disturbances of either the muscle or the neuromuscular junction. These patients are hypersensitive to respiratory depressants used during anaesthesia. A new description is presented of atypical heterozygotous pseudocholinesterases found in a case of dystrophia myotonica. Following familial investigation, a new genetic hypothesis is formulated in an attempt to explain another danger in relation to anaesthesia in these patients.